Stabilized oil composition



H Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE,

STABILIZED OIL COMPO SITION William lL-James, Paulsboro, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application January 20, 1938, Serial No. 185,907

12 Claims. (Cl. 252-47) This invention has to do in a general way with of mineral oil has made possible the marketing hydrocarbon oil compositions and is more parof motor oils of higher viscosity index than hereticularly related to refined viscous petroleum oils tofore has been available, but that these solvent which have been stabilized against the deteriorefined oils of high viscosity index have a derating effects of oxidation by the incorporation cided tendency to corrode hard bearings, such as therein of a small amount of an antioxidant or the cadmium-silver alloy type of bearings. The oxidation inhibitor. compounds contemplated by this invention as As is well known to those familiar with the art, corrosion inhibitors I have found to be particurefined viscous petroleum oil fractions, such as" larly valuable as additive ingredients for solvent 19 transformer oils, turbine oils, motor oils, and the refined oils to inhibit the corrosive action of such i like, which have been refined by treatment with oils on hearing materials of this character, and sulfuric acid or by other methods such as by 801- it is therefore a further object of this invention vent refining, are prone to deterioration, due to to provide a method for protecting alloy bearings, the effects of oxidation reactions, under the norsuch as cadmium-silver bearings, from the cormal conditions of use at elevated temperatures, rosive action of solvent refined motor oils by particularly when in contact with metals. This maintaining within the lubricating film between oxidation results in the formation of acidic the bearing surfaces a compound of the type deproducts which decrease the insulating or discribed. electric strength of the oil, thereby diminishing As has been previously stated, the N,N'-dithioits usefulness in such applications as transformers bis-dialkylamines contemplated by this invention 20 and the like, and which are corrosive in nature can be obtained by the reaction of a sulfurchloand thereby decrease the usefulness of the oils ride on a dialkylamine. To illustrate the methfor lubrication. 0d of synthesizing these compounds the follow- This invention has as its object the provision ing example is given: 4 moles (628 grams) of 5 of refined viscous petroleum oils which are subdiamylamine was added to 800 cc. of benzene in stantially stable against oxidation under normal a reaction vessel. One mole (135 grams) of sulconditions of use and of a method of protecting fur monochloride diluted with 200 cc. of benzene such oils against oxidation. was then gradually added to the amine solution.

My invention is based upon the discovery of It was necessary to employ two equivalents of the fact that materials obtained as the reaction amine, since two moles of the amine were con- 80 product of an alkylamine and a chloride of sulsumed in the formation of a hydrochloride salt fur, when blended with refined viscous petroleum which was apparently unreactive with the suloils of the types above referred to, will substanfur monochloride. After the sulfur monochlotially stabilize such oils against the deteriorating ride had been added, the mixture was cooled and effects of oxidation. stirred until the heat of reaction had been dis- 35 The oil stabilizing compounds contemplated by sipated; the amine hydrochloride was filtered off this invention, which may, for the purpose of and the benzene removed from the filtrate by identification, be termed N,N-thio-bis-alkyldistillation. Any unreacted diamylamine was amines, are characterized by the fact that they removed by distilling under reduced pressure.

0 contain sulfur linked at least by one valence The final product may be water-washed if debond to nitrogen. These compounds are obsired, but it was found to be equally effective as tained as indicated above by the interaction of a corrosion inhibitor whether washed or not. sulfur chlorides, such as sulfur monochloride, N,N'-dithio-bis-dibutylamine and N,N'-dithio- Sulfur dichloride, with p y secondary bis-dicyclohexylamine were also prepared acalkylamines. Compounds of this character percording to this method by the action of sulfur 45 form the function of oxidation and corrosion inmonochloride on dibutylamine and dicyclohexylhibitors when blended with refined viscous amine respectively. petroleum oils of the type above referred to in Th ti hi h probably tak lace in the amounts less than .1%- synthesis described above may be represented by As indicated above, the field of my invention is th following general equation: 50 I not restricted to the so-called highly refined oil of the character of transformer oils and tur- 4BR NEH-Sm RR N NRR bine oils, but also includes solvent refined motor 2RRNH-HC1 oils. In this latter regard, it is well known to in which R and R may both represent alkyl those familiar with the art that solvent refining groups or in which R may represent an alkyl 55 group and R may represent hydrogen, and in which .1: represents the numeral 1 or 2. For the reaction with diamylamine given in the example above this reaction may be represented as follows:

s u)z fl+ a lI l ll)I I I )I The N, N'-dlthio-bis-alkylamines contemplated by this invention have the probable gen eral formula in which R and R both represent alkyl groups, in the case of a N,N'-dithio-bis-dlalkylamine, or in which R represents an alkyl group and R represents hydrogen, in the case of a N,N'-dithiobis-monoalkylamine.

As stated above, the compounds contemplated by this invention are particularly useful in the stabilization of motor oils. To demonstrate this, the following test was performed with a. solvent refined motor oil having a Saybolt Universal viscosity of 55 seconds at 210 F. and a flash point of 435 F. The test comprised bubbling air through a 30 gram sample of oil, heated to 347 F. at the rate of 2,000 ml. per hour over a period of 22 hours, in the presence: of a piece of cadmium-silver alloy hearing. The following table shows the loss in weight in milligrams of the piece of test metal, using the mineral oil alone and the same oil inhibited with N,N'-dithio-bisdiamylamine, N,N'-dithio-bis-dibutylamine and N,N-dithio-bis-dicyclohexylamine, or more specifically, with the products obtained by the reaction of diamylamine, dibutylamine, and dicyclohexylamine with sulfur monochloride according to the exemplary synthesis given above:

In addition to the N,N'-dithio-bis-dialkylamines I have also prepared representative compounds of the N,N'-dithio-bis-monoalkylamine type in which the primary amines mono-butylamine and mono-cyclohexylamine were used as the reactants. These compounds, N,N'-dithiobis-monobutylamine and N,N'-dithio-bis-monocyclohexylamine, although only slightly soluble in oil were found to be effective as corrosion inhibitors in the bubble test described above, as indicated by the data in Table II below:

Table [1 Loss in weight of bearing, milligrams. Compound gi Oil Inhibited alone oil N,N'-ditbio-bis-monobutylamine.- 0.25 110 l N,N-dithio-bis-monocycloherylamine 0. 25 40 1 To illustrate the effectiveness of the compounds contemplated by this invention as means for inhibiting the formation of acidic oxidation prodnets in highly refined oils such as transformer oils and the like, the following test was performed. A neutral transformer oil with Saybolt Universal viscosity of 70 seconds at F. was heated in a glass container for '70 hours at a temperature of 250 F. in the presence of oxygen.

dithio-bis-dialkylamines, and the results of this test, which is known as the Modified German tar test, are given in the table below:

Table III N. N. after aging Oil alone 25.0

Oil+0.l0% N,N'-dithio-bis-dibutylamine- 0.06

Oil+0.l0% N,N'-dithio-bis-diamylamine 0.11 Oil+0.l0% N,N-dithio-bis-dicyclohexylamine 0.06

It will be seen from the above data that the compounds contemplated by this invention, which are represented by the reaction products of dialkylamines and monoalkylamines with sulfur monochloride, possess a high degree of capability of inhibiting the oxidation and corrosion effects of highly refined or solvent refined mineral oils. It will be observed that the percentage of the inhibitive compound required is very low, substantial inhibition being obtained with the use of as little as from 0.01% to 0.25% of the ingradients.

I claim:

1. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a small amount sufiicient to stabilize the oil against the deteriorating effects of oxidation of a N,N'dithio-bis-alkylamine.

2. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a small amount sufiicient to stabilize the oil against the deteriorating efiects of oxidation of a N,N-dithio-bis-dialkylamine.

3. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a small amount sufiicient to stabilize the oil against the deteriorating effects of oxidation of a N,N'-dithio-bis-monoalkylamine.

4. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion sufficient to stabilize the oil against the deteriorating eifects of oxidation of a compound selected from the group consisting of: N,N-dithio-bis-dibutylamine; N,N'- dithio-bis-diamylamine; N,N'dithio-bis-dicyclohexylamine; and N,N'-dithio-bis-monocyclohexylamine.

5. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion suflicient to stabilize the oil against the deteriorating effects of oxidation of N,N'-dithio-bis-diamylamine.

6. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion sufiicient to stabilize the oil against the deteriorating effects of oxidation of N,N'-dithio-bis-dibutylamine.

7. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion sufiicient to stabilize N ,N '-dithio-bis-monobutylamine;

the oil against the deteriorating effects of oxidation of N,N-dithio-bis-dicyclohexylamine.

8. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion sufficient to stabilize the oil against the deteriorating efiects of oxidation of a compound having the probable formula in which R. and R represent alkyl groups.

9. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a minor proportion sufiicient to stabilize the oil against the deteriorating effects of oxidation of a compound having the probable formula in which the R's represent alkyl groups and in which the R"s represent radicals'selected from the group consisting of hydrogen and alwl groups.

10. A mineral oil composition comprising a refined viscous mineral oil having incorporated therein a small amount of N,N'-thio-bis-alkylamine.

cent to about 0.25 per cent of a compound having the general formula \NSS-N/ in which the R's represent alkyl groups and in which the R.s represent radicals selected from the group consisting of hydrogen and alkyl groups.

- WILLIAM H. JAMES. 

